Update version code to 0.21 (#145)

Author: Damien Diehl

app/build.gradle

@@ -21,8 +21,8 @@ android {
         applicationId "com.ddiehl.android.htn"
         minSdkVersion MIN_SDK_VERSION
         targetSdkVersion TARGET_SDK_VERSION
-        versionCode 2100026
-        versionName "0.20"
+        versionCode 2100027
+        versionName "0.21"
         resConfigs "en"
         buildConfigField "long", "BUILD_TIME_UTC", "" + getTime()
         def appId = localProperties.getProperty("app_id")